Feed adjusting mechanism



NOV. 29, 1960 E, L l R 2,961,807

FEED ADJUSTING MECHANISM I Filed Aug. 15, 1957 3 Sheets-Sheet 1 l l q I'm 2.

1" W o M luv 5 4/ v A\\\ j INVENTOR.

[IAROLD Lama/am ATTURNE Y Nov. 29,1960 I E BA| S|GER 2,961,807

' FEED ADJUSTING MECHANISM Filed Aug. 15, 1957 s Sheets-Sheet 2 HIHIIIINNHI INVEN TOR.

HAROLD E. Ems/65R BY 27M Nov; 29, 1960 H. E. BALSIGER 2,961,307

FEED ADJUSTING MECHANISM Filed Aug. 15, 1957 3 Sheets-Sheet 3 INVENTOR HAROLD E. BILLS/GEE ORNEY Unite-d States P mjo" 2,961,807 FEED ADJUSTING MECHANISM Harold E. Balsiger, Waynesboro, Pa., assignor to Landis Tool Company, Waynesboro, Pa.

Filed Aug. 15, 1957, Ser. No. 678,306

13 Claims. c1. 51-165) This invention relates to feed mechanisms for machine tools, particularly of the type in which an adjustment is made after one or more operative cycles to correct the feed setting to compensate for variation from a predetermined size.

The na'tureof the feed mechanism and the method of slidably supporting a'grinding wheel support on a grinding machine is such that it is practically impossible to effect adjustment of the wheel support by increments of .0001" or less.

1 For several years, a size control method has been used which takes a' signal from any. suitable type of work engaging device to advance, the grindingwheel in response to change in size, due to wheel wear and thus 'to prevent oversize work. This method was satisfactory for adjustments of .0001 or more. As the demand for greater accuracy occurred, it was found that even thoughthe feed mechanism advances by the required amount, the tool support may not move at all because of friction, lost motion, windup etc i y 1 This condition may be overcome with an automatic size. control mechanism by providing power means for advancing and retracting the feed mechanism by predetermined increments. Such power means may be connected to a feed mechanism through a common transmission device. However, for the purpose of illustration, separate ratchets are shown for actuating the wheel support in opposite directions. One of these ratchets may be actuated by feeding a predetermined number of ratchet teeth for retracting the feed mechanism. For a grinding operation, the ratchet is advanced in the opposite direction by a number of teeth which may be more or less than said predetermined number; the difference between the number of teeth in thereset ratchet and the number of teeth in the feed ratchet being the amount and direction of adjustment.

It is therefore an object of this invention to provide meansresponsive to variations in sizein successive workpieces to advance or retract the feed mechanism.

Another object is to provide means for effecting minute increments of feed by advancing the feed mechanism by differential amounts rather than-the amount of correction.

Another object is to actuate the corrective means while the wheel support is in a retracted position.

. Pawl and ratchet actuated feed adjusting means are shown for the purpose of illustration. The invention may be used with any type of feed which can be actuated in either direction by predetermined amounts. Suitable feed impulse devices may be used to advance or retract the feed mechanism through a common connecting means.

Figure 1 is a front sectional elevation of a hydraulically operated pawl and ratchet type feed mechanism with the section taken along the lines 1-1 of Figure 2. I

' Figure 2 is a sectional ,end elevation along the lines 2-2 ofFigure1.

Figure 3 is a hydraulic and electric diagram.

Numeral indicates a hand wheel formanually op r a w crating a feed mechanism for feeding wheel lase 18 and grinding wheel 19. Attached to said hand wheel 10 is a sleeve 11 having 'an internal gear 12 formed at one end thereof. Said gear 12 is connected through suitable other gearing to rotate a shaft 13 having a worm gear (not shown) in operative engagement with a worm wheel 14 on feed screw 15. Feed screw 15 is threaded into a rapid feed piston 33 in cylinder 34. Shaft 13 may be moved endwise by slow feed piston 16 in cylinder 17. Another sleeve 20 is mounted and attached in telescoping relation on sleeve 11. Sleeve 20 has three axially spaced ratchet portions 30, 31 and 32. V

Ratchet 30 may be actuated by either of two hydraulically operated pawls 35 and 36. Pawl 35 is attached to piston 40 in cylinder 41. Pawl 36 is attached to piston 42 in cylinder 43. Ratchet 31 serves to advance the'feed mechanism and the grinding wheel 19 to compensate for reduction in diameter of the grinding wheel due to dressing. Ratchet 31 is actuated by pawl 50 on piston 51in cylinder 52. A screw 53 in the left end of cylinder 52 serves to adjust the stroke of piston 51. Ratchet 32 serves to reset the feed mechanism aftera grinding operation and is therefore actuated in the opposite direction from the other ratchets. Ratchet 32 is actuated by pawl 60 on piston 61 in cylinder 62.

The stroke of each of these pawl operating pistons may be adjusted so that each ratchet is rotated through a predetermined number of teeth. The adjusting means consists of an adjusting screw 45 in the left end of cylinder 41 and an adjusting screw 46 in the right end of cylinder 43. The stroke of the reset piston 61 is determined by an adjusting screw 63 in the right end of cylinder 62. The stroke of the oversize compensation pawl 36 includes a greater number of teeth than that of the reset pawl 60. The stroke of the'undersize compensa: tion pawl 35 includes a lesser number of teeth than that of reset pawl 60.

Operation Closing the start switch completes a circuit through the normally closed stop switch to energize control relay ICR.

Control relay contact 1CR1 completes a circuit fromline L1 through line LIA to make current available to other elements in the control panel. Control relay contact 1CR1 also completes a circuit through normally closed control relay contact 11CR3 to make current avail-. able at control relay contacts 21CR2 and 22CR2.

Control relay contact 1CR2 provides a holding circuit from control relay contact 1CR1 through the stop switch to control relay 1CR.

Control relay contact 1CR3 completes a circuit from. line LIA from normally closed limit switch 7LS through normally closed timer relay contact 2TR3 to energize control relay 10CR.-

Control relay contacts 10CR1 and 10CR2 energize valve solenoid C shifting the valve to the right and directing fluid under pressure to the right hand end of the rapid feed cylinder 34 to initiate the rapid positioning movement. The feed valve actuated by valve solenoid C also directs fluid to the upper end of slow feed cylinder 17.

The feed continues at suitably controlled rates untilsparkout limit switch 8LS is closed to energize timer re-. lay lTR.

Normally closed timer relay contact 1TR3 opens the circuit to control relay 10CR. Control relay 10CR is switch 11.8 is opened when the wheel base is retracted and control relay 11CR is deenergized. Normally closed control relay contact 11CR3 is closed.

At the end of the grinding operation, the work is presented to a gauge having electrical contacts 2K and 3K. Undersize work closes contact 2K. Oversize work closes contact 3K. Contact 2K completes a circuit to energize control relay 21CR. Contact 3K completes a circuit to energize control relay 22CR. Closing either control relay contacts 21CR2 or 22CR2 completes a circuit through normally closed timer relay contact 2TR2 to energize control relay 13CR. Control relay contacts 21CR2 or 22CR2 also completes a circuit to energize timer relay ZTR.

When timer relay 2TR times out, a circuit is completed from control relay contact 21CR2 or control relay contact 227CR2 through timer relay contact 2TR1 to energize timer relay 3TR. Timer relay 3TR is held through timer relay contact 3TR3 bypassing timer relay contact 2TR1.

Control relay contacts 13CR1 and 13CR2 complete a circuit to energize valve solenoid E. The valve is shifted to the left and directs fluid to the feed reset pawl piston 61. The reset ratchet 32 is actuated a predetermined amount, for example, ten teeth.

Timer relay 2TR, which is energized at the same time, times out after an interval suflicient to permit the feed reset to occur. At the end of the interval, timer relay contact 2TR2 opens, deenergizing control relay 13CR and valve solenoid E. The valve is centered by springs and both sides connected to exhaust.

Constant pressure at the right hand end of the reset pawl piston 61 and dress compensation piston 51 resets the pawls 50 and 60.

Timer relay 3TR times closed after an interval suflicient to permit the resetting of the feed reset pawl piston 61.

Timer relay contact 3TR1 closes to complete a circuit through either control relay contact 21CR3 or control relay contact 22CR3. If the gauge electrical con ac 2K closes, indicating undersize work, control relay ctn c 21CR3 closes a circuit through normally closed timer re lay contact 4TR2 to energize control relay 14CR and a circuit to energize timer relay 4TR.

Control relay contacts 14CR1 and 14CR2 complete a circuit to energize valve solenoid F. The valve is shifted to the left and fluid is directed to the right hand end of the pawl piston 42 for eflecting undersize compensation. This pawl and ratchet mechanism may be set to advance the ratchet by nine teeth or one tooth less than the reset ratchet was moved in the opposite direction. Thus, the wheel will be advanced by one tooth, say .0001" short of the point from which it was reset after the preceding cycle.

Timer relay 4TR times out, after an interval suificient to elfect the undersize compensation movement of piston 42.

Timer relay contact 5TR3 provides around timer relay contact 4TR1.

Timer relay contact 4TR2 opens, deenergizing control relay 14CR. Valve solenoid F is deenergized and returns to central position connecting the right hand side of the undersize compensation pawl piston with exhaust a holding circuit so that the constant pressure at the opposite end of the piston resets the piston to the right.

When timer relay 4TR times out, timer relay contact 4TR1 is closed energizing timer relay STR. Normally closed timer relay contact 5TR4 opens, deenergizing control relay 21CR. Control relay contact 21CR3 opens, deenergizing and resetting timer relay 4TR. Control relay contact 21CR3 also deenergizes timer relay 5TR and closes timer relay contact 5TR4 to reset the holding circuit from control relay 21CR.

If the work presented to the gauge is oversize, contact 3K is closed and control relay 22CR is energized. A holding circuit is completed through control relay contact 22CR4 and normally closed timer relay contact 7TR4.

Control relay contact 22CR2 repeats the operation of the control relay 130K and timer relays ZTR and 3TR as described above.

Control relay contact 22CR3 completes a circuit through normally closed timer relay contact 6TR2 to energize control relay 15CR. Control relay contact 22CR3 also completes a circuit to energize timer relay 6TR. Timer relay contact 6TR3 closes to provide a holding circuit for timer relay 6TR.

Control relay contacts 15CR1 and 15CR2 complete a circuit to energize valve solenoid G. The valve moves to the right and directs fluid under pressure to the oversize compensation pawl piston 42. Pawl 36 and ratchet mechanism may be set to advance the ratchet by eleven teeth or one more than the reset ratchet was moved in the opposite direction. Thus, the grinding wheel will be advanced to a point one tooth or .0001" beyond the point from which it was reset after the preceding cycle.

Timer relay 6TR times out and opens timer relay contact 6TR2 after allowing suflicient time for the oversize compensation pawl and ratchet mechanism to perform its function. Control relay ISCR is then deenergized.

Valve solenoid G is then deenergized and the valve returns to central position in which the left end of the oversize compensation pawl piston is connected with exhaust and the constant pressure on the other end of said piston resets said piston to the left.

Timer relay contact 6TR1 closes to energize timer relay 7TR. Normally closed timer relay contact 7TR4 opens, deenergizing control relay 22CR. Control relay contact 22CR2 opens, deenergizing and resetting timer relay 6TR and also deenergizing timer relay 7TR and closing timer relay contact 7TR4 to reset the holding circuit for timer relay 7TR.

In each case, the reset of the feed mechanism and the subsequent advance adjustment are effected after the grinding wheel has been retracted. If no change in the feed setting is called for, neither the reset nor the adring means is actuated. Correcting the setting of the .eed mechanism is not effected by advancing or retracting the grinding wheel by the amount of correction required. Instead, the correction is the difference between the extent of the reset movement and the subsequent advance movement.

A conventional dressing mechanism is provided which consists of a suitably mounted dressing tool which may be traversed across the grinding wheel 19 by means of a piston slidably mounted in cylinder 71 and connected to said dressing tool (not shown) through piston rod 72. Fluid under pressure is directed alternately to the opposite ends of cylinder 71 by means of a valve 75 which is shifted to the left by means of push-type valve solenoid D, and to the right by a spring 76.

Suitable hydraulic connections from the conduits leading from valve 75 to the opposite ends of cylinder 71 direct fluid under pressure alternately to opposite ends of pawl operating cylinders and 81. Pawls 82 and 83 on pistons 84 and 85 alternately engage ratchet wheel 86 to move it in the same direction. Said ratchet wheel 86 is connected to a suitable mechanism for feeding the dressing tool (not shown) into engagement with grinding wheel 19.

Valve solenoid D is energized when control relay contacts 12CR1 and 12CR2 are closed. Control relay 12CR is energized by closing the dresser switch 90. Control relay contact 12CR3 in the circuit to control relay 12CR is closed to hold the circuit when switch 90 is released. At the end of the first pass of the dresser across the grinding wheel 19, valve solenoid F in the circuit to control relay 12CR is opened by a cam 91 on piston rod 72. Control relay 12CR is then deenergized and control relay contacts 12CR1 and 12CR2 open to deenergize valve solenoid D. Spring 76 shifts valve 75 to the right and reverses the traverse movement of the dresser.

At the end of the reverse movement, cam 92 on piston rod 72 closes limit switch LS7 thus setting up the circuit for controlrelay 12CR so that when dresser switch 90 is closed, control relay contact 12CR3 will again close the circuit to control relay 120R.

In a machine of this type, the dressing operation is usually initiated automatically. For the purpose of illustration, however, switch 90 is actuated manually.

I claim:

1. In a machine tool, means for making small increments of adjustment betweenfrelatively movable elements comprising means for moving one of said elements away from operative position a predetermined amount which is greater than the amount ofsaid increment of adjustment, and selective means operable thereafter for returning said element to operative position a distance different from said retracting movement bythe'amo'unt of said increment of adjustment.

2. A feed mechanism formachine tools including a feed screw and nut, means for rotatably" adjusting one of said elements, connections between said adjusting means and said feed screw and'nut, said adjusting means including power means for retracting said..feed mechanism a predetermined amount, power means to advance said feed mechanism a predetermined amount more than the amount of retraction, and a third power means for advancing the feed mechanism a predetermined amount less than the amount of retraction.

3. In a machine tool, means for making increments of adjustment between relatively movable elements including power means for moving one of said elements away from operative position a predetermined amount greater than the amount of increment of said adjustment, power means for advancing said feed mechanism a predetermined amount more than the amount of retraction, and other power means for advancing the feed mechanism a predetermined amount less than the amount of retraction.

4. A feed mechanism for machine tools including a feed screw and nut, means for rotatably adjusting one of said elements, connections between said adjusting means and said feed screw and nut, said adjusting means including means for retracting said feed mechanism a predetermined amount, and selective means operable thereafter for advancing said feed mechanism a distance different from said retracting movement.

5. In a machine tool, a bed, a carriage movably mounted on said bed, means for effecting a rapid positioning movement of said carriage relative to an operative position, means for effecting a slow feeding movement of said carriage including a feed screw and nut, means for moving one of said membens incrementally to advance said carriage for a machining operation including two ratchet wheels, connections between said ratchet wheels and said feeding means, two pawls for actuating one of said ratchet wheels, one of said pawls being adapted to rotate said ratchet wheel a predetermined amount in one direction, the other of said pawls being adapted to advance said ratchet wheel a predetermined amount less than said first mentioned pawl, a third pawl being adapted to rotate its ratchet wheel and the feed mechanism in the opposite direction apredetermined amount intermediate the amounts actuated by the first two pawls, and means for effecting operation of said first two pawls when said carriage is out of operative position.

6. In a machine tool, a bed, a carriage movably mounted on said bed, means for effecting a rapid positioning movement of said carriage relative to an operative position, means for effecting a slowv feeding movement of said carriage including a feed screw and nut, means for moving one of said members incrementally to ad- Vance said carriage for a machining operation including two ratchet wheels, connections between said ratchet wheels and said feeding means, two pawls for actuating one of said ratchet wheels, one of said pawls being adapted to rotate said ratchet wheel a predetermined number of teeth in one direction, the other of said pawls being adapted 'to advaiice said ratchet wheel a predetermined number of teeth less than said first mentioned pawl, a third pawl being adapted to rotate its ratchet wheel and the feed mechanism in the opposite direction a predetermined number of teeth intermediate the amounts actuated by the first two pawls, and means for effecting operation of saidfirst two pawls when said carriage is out of operative position. Y

" 7.-In :a machine tool, a bed, a carriage movably mounted on said bed, means for effecting a rapid positioning movement of said carriage relative to an operative position, means forefiecting a slow feeding movement of said carriageincluding a'feed screw and nut, means for moving one of said members incrementally to move said carriage for a machining operation including two ratchet wheels, connections between said ratchet wheels and said feeding'means, two pawls for actuating one of said ratchet wheels, one of said pawls being adapted to rotate said ratchet wheel in increments of a pre.-- determined number of teeth in one direction, the other of'said pawls being adapted to advance said ratchet wheel a predetermined amount less than said first mentioned pawl, a third pawl being adapted to rotate its ratchet wheel and the feed mechanism in the opposite direction a predetermined amount intermediate the amounts actuated by the first two pawls.

8. In a machine tool, a bed, a carriage slidably mounted on said bed, means for effecting a rapid positioning movement of said carriage relative to an operative position, means for effecting a slow intermittent movement of said carriage on said bed including a feed mechanism, means for actuating said feed mechanism incrementally to feed said carriage relative to a workpiece, a gauge for measuring a finished workpiece, means to move said feed mechanism by a predetermined amount to reset said feed mechanism after a predetermined number of grinding operations, means to move said feed mechanism in the opposite direction for amachining operation, connections between said gauge and said feed mechanism to advance said carriage a distance greater than the amount of reset if the gauged workpiece indicates oversize, and to advance said carriage by a distance less than the amount of reset if the gauged workpiece indicates undersize, and means for effecting operation of said advancing means in response to said positioning movement away from grinding position.

9. In a machine tool, a bed, a carriage slidably mounted on said bed, means for effecting a rapid positioning movement of said carriage relative to an operative position, means for effecting a slow intermittent movement of said carriage on said bed including a feed mechanism, means for actuating said feed mechanism incrementally to feed said carriage relative to a workpiece, a gauge for measuring a finished workpiece, means to move said feed mechanism by a predetermined amount to reset said feed mechanism after a predetermined number of grinding operations, means to move said feed mechanism in the opposite direction for. a machining operation, connections between said gauge and said feed mechanism to advance said carriage a distance greater than the amount of reset if the gauged workpiece indicates oversize, and to advance said carriage by a distance less than the amount of reset if the gauged workpiece indicates undersize.

10. The method of making extremely small increments of adjustment between machine elements having co-acting surfaces which consists in moving said machine elements away from operative position an amount substantially greater than the amount of said increment, and thereafter returning said machine elements to operative position a distance different from said retracting movement by the amount of said increment.

11. A feed mechanism for machine tools including a feed screw and nut, a pawl and ratchet mechanism, connections between said pawl and ratchet mechanism nd said feed screw and nut, said pawl and ratchet mechanism having a pair of ratchet wheels, a power actuated pawl for actuating one of said ratchet wheels to retract said feed mechanism apredetermined amount, a pair of power-operated pawls for engaging one of said ratchet wheels to advance the feed mechanism for a machining operation, one of said pawls being adjusted to advance the feed a predetermined amount more than the amount of retraction, the other of said pawls being adjusted to advance the feed a predetermined'amount less than the amount of retraction.

12. A feed mechanism for machine tools including a feed screw and nut, a pawl and ratchet mechanism, con nections between said pawl and ratchet mechanism and said feed screw and nut, said pawl and ratchet mechanism having a pair of ratchet wheels, a power actuated pawl for actuating one of said ratchet wheels to retract said feed mechanism a predetermined amount, a pair of power-operated pawls for engaging one of said ratchet wheels to advance the feed mechanism for a machining operation, one of said pawls being adjusted to advance the feed a predetermined amount more than the amount of retraction, the other of said pawls being adjusted to advance the feed a predetermined amount less than the amount of retraction, a gauge mechanism having means responsive alternately to oversize and undersize workpieces, and connections from said means to actuate one of said feed advancing pawls, and other connections from said means to actuate the other feed advancing pawl.

13. A feed mechanism for machine tools including a feed screw and nut, means for rotatably adjusting one of said elements, connections between said adjusting means and said feed screw and nut, said adjusting means including power means for retracting said feed mechanism a predetermined amount, a second power means to advance said'feed mechanism a predetermined amount more than theamountof retraction, a third power means for advancing the feed mechanism a predetermined amount less than the amount of retraction, and gauge means for selectively actuating oneof said power advancing means.

References Cited in the file of this patent UNITED STATES PATENTS 2,378,903 Baldenhofer June 26, 1945 

